A three-phase inverter for uninterruptible power supply (UPS) is required to generate high-quality voltage under various loads with fast dynamic response, high tracking accuracy, and good robustness. To fulfill the aforementioned requirements, a plug-in multiple resonant control (MRSC) strategy is propounded for a three-phase UPS inverter to compensate AC signals and their harmonics. The proposed control scheme takes advantages of both multiple resonant controllers and the deadbeat controller, where the deadbeat controller furnishes rapid response and sufficient robustness, while the multiple resonant controllers offer precise recompense of the periodical signal. This paper also provides a design approach and gain tuning rules for the proposed control scheme. An experimental study on the plug-in MRSC scheme is carried out. The test verifies that the MRSC strategy is able to produce high-quality voltages with good robustness.